The microscopic examination of tissue or tissue components is a common and valuable practice in both medicine and biology. Such procedures typically rely on the visual appearance of the tissue which is often enhanced by the use of specialized stains that bind to certain tissue components, foreign bodies, or the products of cellular processes.
With the advent of computer technology, it has now become possible to automate many of the manual examination procedures by using a computer-controlled microscope to image a microscope slide, digitize the images, and place them into the memory of a computer for subsequent analysis, display, and storage.
Most automated microscope imaging systems do not have the ability to predict in advance what a pathologist or user may determine is interesting or important on a slide containing a biological sample. Current automated systems, therefore, capture and store high-quality, images of the entire microscope slide. Using a high-power objective, such as a 60× or 100× objective, the field of view is quite small relative to the overall area of the biological sample. Therefore, the system takes many images to cover the entire area of the microscope slide. Each high-power image requires significant storage capacity. A database of information and images of an entire microscope slide can quickly begin to overwhelm available resources. In addition, only a fraction of the information and images saved may be of any interest or be used by a pathologist or other user in making a diagnostic evaluation. The remaining information and images may be of little to no value.
Improving automated imaging systems depends on the ability of the system to automate portions of the tissue examination process that would otherwise be manually performed by a pathologist or other user. This, in turn, relies on the ability of the system to identify not only the sample on the slide from other content, but to distinguish, without operator intervention, those portions of the sample necessary for making a diagnostic evaluation from those portions that are not needed. A high magnification image can be stored for each confirmed object of interest. The images are then available for retrieval by a pathologist to review for final diagnostic evaluation.
One current method of minimizing the storage capacity requirements of an automated microscope imaging system is to use image compression techniques. An imaging system captures high-power images of the entire microscope slide and each image is then compressed in order to reduce its storage capacity requirements. However, most compression techniques in use today utilize compression algorithms that are lossy and thus do not perfectly recreate the original image, i.e., the image suffers some distortion during the compression algorithm's encoding and decoding process.
U.S. patent application Ser. No. 2003-0163031, entitled, Method and System for Providing Centralized Anatomic Pathology Services, describes a method of providing centralized anatomic pathology services. A master storage, such as a database, of pathology information is maintained, the storage being accessible by pathologists associated with any regional laboratory via a communications link. Tissue samples requiring pathology processing are collected from a medical entity located in a first geographic region by a regional pathology laboratory. The tissue is processed, and a tissue slide is created. A digital, diagnostic quality image of the tissue slide is created and stored in the master storage. A pathologist, who may be remotely located with respect to the first geographic region, is provided with access to the stored diagnostic image via the communications link, to enable diagnosis by the pathologist without physical possession of the slide. The digital, diagnostic quality image may be compressed before it is stored in the master storage. The diagnosis may be a primary or a secondary diagnosis. In the case of a secondary or supplemental diagnosis, the pathologist is provided with access to any prior analysis and annotations, stored in the master storage, relating to the diagnostic image.
The '031 patent application, using wavelet compression, provides a means to optimize image storage capacity at the master storage location and transmission time across a communications link to a remote location. However, the wavelet compression method of the '031 patent application utilizes a lossy compression algorithm, whereby the compressed/decompressed image is different from the original digital image. These differences, though they may be subtle, could inhibit a pathologist from making an accurate diagnostic evaluation.
U.S. Pat. No. 6,272,235, entitled, Method and Apparatus for Creating a Virtual Microscope Slide, describes a method and apparatus for constructing a virtual microscope slide made up of digitally scanned images from a microscope specimen. The digitally scanned images are arranged in a tiled format convenient for viewing without a microscope, and for transferring the tiled images for viewing by another at a remote location. Several original microscope views at a low magnification are digitized and stored as digitized images coherently seamed together to-provide an overall virtual, macro image of the specimen at a lower resolution. Several original microscope views at higher magnifications are digitized and stored as digitized images coherently seamed together to provide virtual micro images at higher resolution. A data structure is formed with these virtual macro and micro digitized images along with their mapping coordinates. Preferably, a generic viewing program is also provided in the data structure that allows remote users to manipulate and interpret the tiled images on the user's monitor. Also, the data structure is formed with significantly compressed data so as to be transmitted over low bandwidth channels, such as the Internet, without loss of resolution that would interfere with the analysis at a remotely-located pathologist receiving the data structure over the Internet. The preferred interactive program allows the pathologist to scroll and view neighboring image areas of interest. A marker on the macro image indicates to the user the location of the micro image and assists the user in selecting areas from the macro image to be viewed at higher resolution and magnification.
While the '235 patent provides a means to selectively capture digital images at high magnification, rather than image the entire microscope slide using a high power objective, it relies on the user of the apparatus to manually select a region of interest for high magnification digital imaging. A user examines the macro image or original specimen for significant details. Typically, the user will highlight with a marking pen the areas to be viewed at higher magnification. The user then changes the magnification to a higher power objective, moves the microscope slide to bring the selected region into view, and begins to capture images of the selected region.
U.S. Pat. No. 5,978,498, entitled, Apparatus for Automated Identification of Cell Groupings on a Biological Specimen, describes the detection of cellular aggregates within cytologic samples. An image analysis system with an image gathering system includes a camera, a motion controller, an illumination system and an interface; the system obtains images of cell groupings. The image gathering system is constructed for gathering image data of a specimen mounted on a slide and is coupled to a data processing system. Image data is transferred from the image gathering system to the data processing system. The data processing system obtains objects of interest. A four step process finds cellular aggregates. The first step is acquisition of an image for analysis. The second step is extraction of image features. The third step is classification of the image to determine if any potential cellular aggregates may exist in the image. The fourth step is segmentation of objects which includes the substeps of detecting and locating potential cellular aggregates.